1. Field of the Invention
This invention relates to trailers, especially those suitable for transporting boats and the like, of the type normally drafted or pulled by motor vehicles. Typical of such trailers are those having a frame supported on one or more axles for mounting the running wheels and having a longitudinal tongue including a hitch for attachment to a vehicle.
2. Description of the Prior Art
An increase in leisure time and development of waterway facilities have made boating more popular than ever. This increase in popularity has resulted in more boats and a greater demand for docking space, causing the availability of docking to decrease and the cost of docking to increase. Hence, greater numbers of boat owners than ever before are trailering their boats, even though the size of the boats is also on the increase. Trailering also allows a boat owner considerable flexibility in the choice of recreational water areas.
A necessary but difficult task associated with boat trailering is the loading and unloading of the boat onto or from the trailer. The trailer with boat is backed into the water to the extent necessary to permit the boat to be slipped off the trailer and into the water with a minimum of physical labor. The boat is reloaded on the trailer by again backing the trailer in the water and using a conventional winch mounted forward of the boat trailer with a cable attached to the bow of the boat so that the boat is pulled onto the trailer using the winch and cable.
As boats become larger and larger, it has become increasingly difficult to load and unload a boat onto and from a trailer in the foregoing manner. It is often necessary to back the trailer into the water to such an extent that the rear wheels of the vehicle pulling the trailer are completely submerged. Not only is traction a problem and getting stuck a real possibility, but the water can cause rusting of metal components and other damage.
Finally, while the boat owner is often willing to spend substantial amounts on his boat, he becomes quite frugal in connection with his trailer and the combination of reliability and low cost are a necessity.
To overcome some of the difficulties associated with the loading and unloading of boats onto and from boat trailers, various forms of telescoping or pivotable frame boat trailers have been developed. Such trailers are characterized by the fact that the trailer frame or a part thereof is adapted to move longitudinally or pivot with respect to the trailer so that it is often unnecessary to submerge substantial portions of the trailer or the rear wheels of the vehicle in the water while the boat is launched or reloaded on the trailer. Exemplary of such telescoping and/or pivoting trailers are those disclosed in U.S. Pat. Nos. 2,713,951, 2,856,087, 3,032,353, 3,102,737, 3,138,271, 3,083,986, 3,140,003, 3,142,494, 3,326,573, 3,390,796, 3,822,899, 3,989,266 and 4,050,595. These movable trailer frames have generally met with little, if any, success. It is believed that the complexity of design, low reliability and high cost have prevented such trailers from gaining acceptance.